Walk through Amos, verse by verse, with the great Bible Commentaries of Matthew Henry (1662 - 1714) & Adam Clarke (1760 - 1832)
9:5
And the Lord GOD of hosts is he that toucheth the land, and it shall melt, and all that dwell therein shall mourn: and it shall rise up wholly like a flood; and shall be drowned, as by the flood of Egypt. KJV
{And the Lord God of hosts shall do these things, (he) that toucheth earth, and it shall fail, and all
men dwelling therein shall mourn; and it shall go up as each strand, and it shall float away as the flood of Egypt.} Wycliffe's Bible
The Lord God of hosts is he - So powerful is he that a touch of his hand shall melt or dissolve the land, and cause all its inhabitants to mourn. Here is still a reference to the earthquake.